The designs of modern telecommunication networks are based on Telecommunication Management Network (TMN) principles. The TMN principles define several levels for the management of a telecommunication network. Thereby, each level provides for two functionalities:
(a) A first functionality is the so called managing function for managing entities being assigned to a lower level. The managing functionality is necessary for all levels except for the lowest level.
(b) The second functionality is the so called agent function for communicating with the proximate higher level. The agent functionality is necessary for all levels except for the highest level.
The manager-agent communication is effected via management interfaces, which are defined in an object-oriented environment by means of a communication protocol and an object model. The communication protocol may be for instance Common Object Request Broker Architecture (COBRA), Common Management Information Protocol (CMIP) or Simple Network Management Protocol (SNMP). The object model is often also called a Network Resource Model (NRM). Such interfaces are used for instance in an Universal Mobile Telecommunications System (UMTS) between the Network Element (NE) management level and the NE level and between the Network Management (NM) level and the NE management level.
For starting a monitoring and a controlling of a telecommunication network, a manager initiates requests, which are executed in agent parts of managed entities. Thereby, the manager receives corresponding responses. In order to guarantee an efficient NM, an agent recognizes relevant events within the network, generates so called notifications and transmits these notifications as event reports to the manager being arranged in the next higher level.
For a reliable management of a telecommunication network it is essential that relevant event messages are forwarded as fast as possible and without any failure to the manager system. This requirement can be fulfilled by taking two measures:
A) According to a first measure a manager has to subscribe the desired event messages from an agent. In order to realize this first measure the 3rd Generation Partnership Program (3GPP) standard TS 32.302“Notification Integration Reference Point (IRP): Information Service” defines a so called subscribe operation. Thereby, the manager transmits to the agent a subscription request, which comprises detailed specifications about the type and the parameter values of desired event messages. In addition, the manager can use a so called time-tick parameter, which defines a time span within which a request for the subscription status (get-subscription-status request) to the agent has to be submitted. Therewith, the agent is able also to monitor the availability of the higher-ranking management system.
B) According to a second measure a failure of an agent and/or a failure of the logical connection between an agent and the corresponding manager have to be determined very quickly. In order to realize this second measure a monitoring mechanism has to be implemented at the interfaces between manager and agent. In 3GPP such a monitoring mechanism is standardized as 3GPP TS 32.352 and is called “Communication Surveillance Integration Reference point: Information Service”.
The “Communication Surveillance Integration Reference point: Information Service” is based on the following two principles:
A) The agent periodically transmits a so called heartbeat notification to the manager. From a continuous and correct reception of these heartbeat notifications the manager can conclude that both the agent and the communication through the manager-agent interface are working properly.
B) In order to monitor the reception of heartbeat notifications at regular intervals the manager uses an own timer. The elapsed time of the timer corresponds to the heartbeat period. After having received a heartbeat notification the timer is set again in its initial condition. A time lapse (time-out) of the timer without a new reception of a heartbeat notification shows the manager, that there is a failure in the subsidiary agent system and/or in the communication channel between manager and agent.
The architecture of the Radio Access Network (RAN) of future Long Term Evolution (LTE) networks envisages a flat and decentralized structure of Base Stations (BS), which are denominated evolution Node Base stations (eNodeBs). The absence of controller network elements such as Base Station Controllers (BSC) being used for Global System for Mobile telecommunication (GSM) networks or Radio Network Controller (RNC) being used for UMTS Terrestrial Radio Access Network (UTRAN) requires on the one hand a direct connection between the BS and the management systems such as Element Management System (EMS) or Network Management System (NMS) and on the other hand a peer-to-peer connection between the individual eNodeBs in order to administer the neighborhood relationships between adjacent radio cells.
FIG. 2 depicts the architecture of such a LTE telecommunication network 200, which at the time this application has been drafted has not yet been implemented for commercial purposes. The telecommunication network 200 comprises a first level 210, in which a plurality of eNodeBs 211 is arranged. Each eNodeB comprises an agent part 211a for generating event messages according to the employed object model at the interface to management system and for transmitting these event messages to a management system 221 representing the second level 220 of the telecommunication network 200.
The management system 220 subscribes for heartbeat notifications from each of the eNodeBs 211. The subscription for receiving heartbeat notifications is indicated in FIG. 2 by the arrows 290. The corresponding transmission of heartbeat notifications from the eNodeBs 211 to the management system 221 is indicated by the arrows 291. The above described necessary peer to peer connections are designated with reference numeral 295.
Since it is expected that future LTE networks will comprise a high number of eNodeBs 211, the above described known method for monitoring managed entities will exhibit several disadvantages. In particular a very high number of heartbeat notifications will have to be transmitted to the management system 221 within a short time period. This has the effect, that a high data transmission load in particular to the interfaces in between the first level 210 and the second level 220 and additionally on the management system 221 is produced even if all components of the telecommunication network are in proper operation.
There may be a need for improving the efficiency for monitoring the operational state of a telecommunication network comprising a plurality of managed entities being arranged in a first level.